A multilayer ceramic capacitor has a plurality of internal electrodes stacked along one direction. Therefore, there is a demand that identification of a direction of stack of internal electrodes in a multilayer ceramic capacitor is desired. For example, in a case that a multilayer ceramic capacitor has a square prismatic shape, however, it is difficult to identify a direction of stack of internal electrodes in a multilayer ceramic capacitor based on appearance.
For example, Japanese Patent Laying-Open No. 7-115033 describes a method allowing identification of a direction of stack of internal electrodes in a multilayer ceramic capacitor not based on appearance. Specifically, Japanese Patent Laying-Open No. 7-115033 describes a method of identifying a direction of an internal electrode layer based on intensity of magnetization by applying certain magnetic field to one surface from which an internal electrode layer is not extracted and by measuring a magnetic flux density of a multilayer ceramic capacitor. This method makes use of a difference in measured magnetic flux density between a state that a capacitor is arranged in an orientation in which an internal electrode is substantially in parallel to a magnetic flux (an internal electrode is perpendicular to a bottom surface as a capacitor) and a state that a capacitor is arranged in an orientation in which an internal electrode is substantially perpendicular thereto (an internal electrode is horizontal to the bottom surface as a capacitor).
A difference in measured magnetic flux density, however, is very small between a case that a direction of stack of internal electrodes and a direction of a magnetic flux are in parallel to each other and a case that a direction of stack of internal electrodes and a direction of a magnetic flux are perpendicular to each other. In addition, a measured magnetic flux density is significantly dependent on positional relation among a magnet, a sensor probe, and a capacitor. In particular, in a multilayer ceramic capacitor small in size, influence by positional relation among a magnet, a sensor probe, and a capacitor on a measured magnetic flux density is great.
Thus, since a difference in magnetic flux density measured at the time when a direction of stack is different is small and a measured magnetic flux density is significantly different depending on a position of a capacitor at the time of measurement, it is difficult to accurately identify a direction of stack of a multilayer ceramic capacitor with the method described in Japanese Patent Laying-Open No. 7-115033.
This problem will more specifically be described. For example, a case that a magnetic flux density of a multilayer ceramic capacitor having a length dimension of 1 mm, a width dimension of 0.5 mm, and a height dimension of 0.5 mm and having a capacitance of 4.7 μF is measured under a certain measurement condition is assumed. A maximum magnetic flux density of this multilayer ceramic capacitor in a case that a direction of stack of internal electrodes is in parallel to a direction of a magnetic flux is approximately 53.6 mT. On the other hand, a maximum magnetic flux density of this multilayer ceramic capacitor in a case that a direction of stack of internal electrodes is perpendicular to a direction of a magnetic flux is approximately 52.3 mT. Therefore, a difference in maximum value for a magnetic flux density of this multilayer ceramic capacitor between a case that a direction of stack of internal electrodes and a direction of a magnetic flux are in parallel to each other and a case that they are perpendicular to each other is only 1.3 mT. Therefore, a difference in maximum value for a magnetic flux density between the case that the direction of stack of internal electrodes and the direction of the magnetic flux are in parallel to each other and a case that they are perpendicular to each other is only 2.4% as compared to the maximum value for the magnetic flux density in the case that the direction of stack of the internal electrodes and the direction of the magnetic flux are in parallel to each other.
A magnetic flux density of a multilayer ceramic capacitor in which a direction of stack of internal electrodes and a direction of a magnetic flux are in parallel to each other at the time when a position of measurement in a multilayer ceramic capacitor is displaced by 0.3 mm from a central position of the multilayer ceramic capacitor is approximately 52.3 mT, which is substantially equal to the maximum value for the magnetic flux density of the multilayer ceramic capacitor in the case that the direction of stack of the internal electrodes and the direction of the magnetic flux are perpendicular to each other (a case that a measurement position is located at a central position of the multilayer ceramic capacitor). Thus, when a measurement position in a multilayer ceramic capacitor may vary by 0.3 mm or greater, identification of a direction of a multilayer ceramic capacitor is difficult. This problem is noticeable because it is more difficult to set a measurement position to a central position as a multilayer ceramic capacitor is smaller in size, for example, when each dimension is smaller than a length dimension of 1 mm, a width dimension of 0.5 mm, and a height dimension of 0.5 mm.
With the method described in Japanese Patent Laying-Open No. 7-115033, a magnetism generator and a magnetic sensor should be arranged to be opposed to each other, with a capacitor lying therebetween. Therefore, the method described in Japanese Patent Laying-Open No. 7-115033 is restricted in terms of arrangement of the magnetism generator and the magnetic sensor. Therefore, the apparatus identifying a direction of a capacitor described in Japanese Patent Laying-Open No. 7-115033 is disadvantageous in low degree of freedom in design of an apparatus.